In the future could LR3 and Elements 8 be brought in line or am I missing something (apart from PEN support).

As far as Lightroom goes, it has nothing directly to do with Camera Raw...doesn't use the plug-in at all. The processing pipeline is built in not modifued via plug-in.

If you are in a hurry, download the DNG Converter 5.5 and convert your files to DNG...then Lightroom 2.4 and Camera Raw 5.4 will read them.

As far as Adobe providing developmental builds, if you don't want them in advance of the actual release, you don't need to get all excited...just wait for the general release. Most people actually appreciate the fact that Adobe does this instead of complaining that the builds are not designed to work in Elements....